The Cryotop method for oocyte vitrification is classified as "open system", which means that it requires direct contact with liquid nitrogen during the vitrification process. The system has an external straw to protect the samples during storage, but the device is not hermetically sealed. Instead closed systems are devices that are hermetically sealed before vitrification and remain sealed during storage. Open systems have proven highly effective in achieving similar outcomes with vitrified oocytes compared to those achieved with fresh ones. On the contrary, closed systems have failed to be as effective as open ones when used for oocyte vitrification. Although open systems have proven to be highly efficient, where many other methods have failed, they have been related to a theoretical risk of contamination due to direct contact with liquid nitrogen. Though to date there have been no reported cases of transmission of disease after cryo-transfers either for slow freezing or vitrification, some European countries prohibit the use of open systems for vitrification. In this study, we will evaluate the results after the donor oocyte vitrification, using a modification of a current device (Cryotop®), which makes it capable of being hermetically sealed. The current study is a prospective randomized trial aimed to assess the outcome of ovum donation cycles conducted with vitrified oocytes using the closed device versus oocytes vitrified using the traditional open device.